A new vaccine utilizing a patient’s own immune cells has produced encouraging anti-cancer responses in individuals with advanced colorectal or advanced non-small cell lung cancer (NSCLC), according to results recently presented at the 37th Annual Meeting of the American Society of Clinical Oncology.
The majority of colorectal cancer cells and some lung cancer cells display a protein on their surface called the carcinoembryonic antigen (CEA). Through mechanisms not clearly elucidated, CEAs are not recognized by the patient’s immune system when they are presented on cancer cells in the body. Researchers have recently been investigating novel strategies to stimulate the immune system to recognize CEA as foreign which would cause an attack on cancer cells presenting this antigen. Previous studies have indicated that the immune system recognizes antigens such as CEA as foreign when they are re-infused into the patient. Once recognized as foreign, the immune system attacks cancer cells elsewhere in the body that display the antigens.
One strategy for stimulating the immune system against CEA that is still being evaluated in clinical trials involves the re-infusion of CEA plus dendritic cells in the form of a vaccine. Dendritic cells are cells of the immune system whose function is to present foreign antigens to T-cells. T-cells then attack cells in the body which display these antigens. The process of producing this biological vaccine involves the following: the patient first receives an agent which stimulates the body to produce more than usual amounts of dendritic cells. The patient’s blood is then drawn and dendritic cells are collected. In the laboratory, the collected dendritic cells are combined with a part of the CEA antigen. This complex is then injected under the patient’s skin.
Researchers from Stanford recently conducted a clinical trial evaluating this form of therapy in 12 patients with either advanced colorectal cancer or advanced NSCLC. Following treatment, one-third of these patients achieved an anti-cancer response for at least 6 months, with 2 patients achieving a complete disappearance of their cancer. One of the complete responders remains cancer-free at one year following treatment. There were no adverse complications caused by the treatment in this clinical trial.
These results are encouraging as patients with advanced colorectal or advanced NSCLC often are left with few treatment options. Future clinical trials involving this therapeutic strategy are aimed at evaluating patients earlier in the course of the disease, with the hope that their immune systems will be stronger and an even more potent immune response will be elicited. Patients with colorectal cancer or NSCLC may wish to speak with their physician about the risks and benefits of participating in a clinical trial further evaluating this strategy or other promising treatments. Two sources of information about ongoing clinical trials include comprehensive, easy-to-use listing services provided by the National Cancer Institute ( cancer.gov) and eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients. ( Proceedings from the 37thAnnual Meeting of the American Society of Clinical Oncology, Abstract 1085, San Francisco, CA, May, 2001)
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